The use of a single assembly for mounting on a seeder and dispensing both fertilizer and seed in a single pass is known from prior U.S. Pat. No. 4,762,075 of one of the present inventors (Halford) and from subsequent U.S. Pat. Nos. 5,331,907 and 5,398,851 of Beaujot. Also reference is made to U.S. Pat. No. 6,142,085 of Halford et al which discloses another assembly of the same general type using a hydraulic cylinder to provide the necessary forces and U.S. Pat. No. 5,947,209 of Halford et al which shows a construction of shank for use in a machine of this type.
These assemblies generally include a furrowing element or knife for producing a furrow in the ground as the assembly is pulled across the ground and a fertilizer feed tube for depositing fertilizer directly behind the furrowing element. A second delivery member including a dispensing tube is provided spaced rearwardly of and usually but not necessarily laterally offset from the furrowing element, for depositing the seed in ground spaced at a position preferably offset to one side from the fertilizer and preferably offset above. A packer wheel then follows for providing depth control and packing soil above the seed.
Generally a single biasing element, but in some cases more than one such element, is provided in the above arrangements for urging both the furrowing element and the packer wheel downward to engage the ground. In some known assemblies however the forces are more directed to one element rather than the other. When the forces are not properly distributed, taking into account the ground conditions which may vary widely, the resulting seeding operation becomes less effective. The above patent U.S. Pat. No. 4,762,075 of Halford provides an arrangement using a spring for applying force to the knife and a separate spring for applying forces to the packer and second delivery member. In practice both are adjustable to provide independent adjustment of the separate forces for best control. The above patents of Beaujot provide instead an arrangement using a hydraulic cylinder to apply the force. However these do not allow the distribution of force between the packer wheel and the second distribution member on one assembly and the furrowing element or knife on a second assembly to be adjusted independently and thus the seeder is less suited to varying conditions of the ground to be seeded.
A research machine which was used in the 1960s in Sweden was developed by researchers Heinonen and Huhtapalo provided an arrangement generally of the above type which included a first furrowing element for engaging the ground and for applying fertilizer and the second furrowing element behind and offset to one side from the first for applying seed with the second attached to a packer wheel for guiding the depth of the seed. This machine known as the “Viktoria” machine was used for research but did not lead to any commercial machines of that type with the commercial development arising from the research being directed to alternative types of machines known as “mid row banding”. The Viktoria machine mounted the fertilizer element and the seeding/packer element as separate components on a frame with a hydraulically biased rocker shaft applying forces onto the fertilizer component and a spring connected between the packer arm and the frame providing biasing forces on the packer wheel. Drawings of this device are shown in a paper entitled FERTILIZER PLACEMENT FOR SMALL GRAINS by HEINONEN et al dated 15th Apr. 1978.
Machines of the above type shown in the Halford and Beaujot patents are generally used for single pass, minimum-tillage seeding and fertilizing. Machines of this type have become widely used and are manufactured under the arrangements as shown in the above patents by the companies Conserva Pak and Seed Hawk. While machines of this general type and as disclosed herein are primarily proposed for minimum tillage applications, it is not essential that they be so used and in many cases the same machine can be used in tillage systems where the conditions of crop residue and soil impaction are less rigorous.
A number of further devices, one example of which is shown in U.S. Pat. No. 5,562,054 of Ryan issued Oct. 8, 1996, include a furrowing element which is engaged into the ground by force from the hydraulic cylinder. The second material delivery system is pivotally mounted on the rear of the shank and floats on a parallel linkage system with a relatively small spring force applied by a mechanical spring. An arrangement of this type has some application in relatively light soils but is unsuitable for wide application and for zero till applications.